Decoupled Terminal Sliding Mode Control of Two-link Flexible Manipulators with Motor Dynamics

The decoupling control of two-link flexible manipulators with uncertain parameters and joint motor dynamics is investigated by combining terminal sliding mode (TSM) and output redefinition in this paper. The linear combination of joint angles and flexible modes is chosen as the redefined output to overcome the inherent non-minimum phase characteristics of flexible manipulators; correspondingly the system is decomposed into an input-output subsystem with motor dynamics and an internal dynamic subsystem with uncertain disturbances. A TSM controller is designed for the robust stability of input-output subsystem as well as to transfer the internal dynamics into zero dynamics. The stability of zero dynamic subsystem is proved to be related to the redefined parameters. Finally the steady-state error of the tip position for each link is deduced by Lyapunov stability theory. Simulation results validate the proposed scheme.